The tweet is certainly cryptic. So I reached out to Del Rey's Erich Schoeneweiss for clarification. Will this announcement reveal a completely new book or provide, say, a title and cover art for a book whose existence is already known to fans (like one of the upcoming books in the "Rebels" series)?

"It's a book we haven't talked about at all publicly," Schoeneweiss told me. He characterized the announcement as the former of my two possibilities: "we're going to reveal a book you had no idea existed."